1. Field of the Invention
This invention relates to holographic image display systems, and to related methods and processor control code.
2. Description of the Related Art
We have previously described techniques for displaying an image holographically—see, for example, WO 2005/059660 (Noise Suppression Using One Step Phase Retrieval), WO 2006/134398 (Hardware for OSPR), WO 2007/031797 (Adaptive Noise Cancellation Techniques), WO 2007/110668 (Lens Encoding), and WO 2007/141567 (Colour Image Display). These are all hereby incorporated by reference in their entirety.
Advantages of holographic image display techniques include a compact optical system and increased optical efficiency as compared with conventional display systems. However the techniques we have previously described are relatively computationally expensive when displaying high-resolution images and, in a hardware (ASIC) implementation the resolution is closely tied to the hardware configuration. In an OSPR-type approach, where multiple spatially-coincident temporal holographic subframes are displayed for each image frame, the power consumption may be reduced by employing multi-phase rather than binary phase modulation, but nonetheless further power savings are desirable. Depending upon the implementation of the technique, more SLM (Spatial Light Modulator) pixels may be employed than are seen as image pixels, which can increase cost and make miniaturisation difficult. A high contrast image display can also be difficult to achieve.
It is therefore desirable to be able to increase the efficiency and image quality of holographic image display systems, and to further reduce their size.